Task Definitions

[JohnB]

I am trying to understand Fixed Units, FIxed Duration and Fixed Work and
think I have it down and then project does not work like I want it to (or
most likely i am doing something wrong). As an Example, I want to assign two
resources to a specific task. the task Work is 32 hours. I want to assing
70% of those hours to one resource and 30% of the hours to the other
resource. Project keeps changing my work when I perform the above. How do I
keep the work at 32 hours. thanks

 

[Jan De Messemaeker]

Hi JohnB,

(Oh your name reminds me of the Beach Boys, nice musical memory it is)
In Task Usage, fill in work 22.4 resp. 9.6 hours for the two assignments.
HTH

 

[Steve House [MVP]]

A couple of things to know about.

First of all, note the basic equation Project always follows W=U*D, Work
equals Units times Duration. This is always - always - going to be true.
32 man-hours Work = 32 hours Duration * 100% Units or it could also be 64
hours Duration * 50% Units or some other combination.

Second, if you assign 2 resources to a task at 30% and 70% respectively, it
does NOT mean that they are splitting the work 30/70. 30% means that 30% of
the time the resource is spending on the task is converted to useful work.
If the task duration was 3 days, 24 hours, and you assign a resource to it
at 30%, his attention is divided between the task at hand and other things
and so he will do 8 man-hours of work on this particular task over a three
day period. In other words, he will get done in 3 days what he COULD have
done in 1 day if he didn't have any distractions.

Third, the task type determines what happens when you EDIT resource
assignments that have already been made. I have Joe assigned 100% to a task
that takes 5 days, 40 hours. Becuase he's assigned 100%, the work he's
producing is also 40 man-hours. But never ever forget that hours of work
and hours of duration are two completely different, albeit related,
critters. I now edit his assignment, changing the Units to 50%. I could be
doing that for a couple of reasons. One is that it is really a 20 man-hour
task but I don't need it done any sooner than Friday so I'll let him work on
it at his leisure over the 5 days duration. Makes the task Fixed Duration,
change the assignment, and Project recalculates Work. Or it could be that
this task really does require 40 man-hours of work but I have some other
priorities and prefer Joe to work 4 hours a day on this task and 4 hours a
day on something else. I make the task Fixed Work, edit the assignment, and
Project recalculates the Duration to be 10 days - it'll take him longer to
get the work done but my other priorities dictate I'll just have to live
with it.

So to your example. Before going further the first question to ask is what
do you mean by it being a 32 hour task, if it's work how do you KNOW it's a
32 man-hour task and where did you enter that fact into Project? When you
want to split the work between the two resources do you want one guy to work
on it for a while and then the other take over or do you want them to work
together until the first guy finishes his part of the work and then the
other works on alone or do you want the 70% guy to work full speed while the
other works part of each day along with him, or just what are you looking
for in the schedule? It's possible to do all of those things but you have
to decide first where you want to end up. In other words, 32 man-hours
split 70/30 isn't enough information to set up the scenario.

 

[JohnB]

steve --- Thanks for your very detailed explanation. My task is 32 hours
long. I am going to assign two resources to the task that can work in
parallel to complete the task. One resource has the lion share of the work
or 70% of the 32 hours and the other finishes the 30% remaing work. The
overall work is 32 hours but the duration is reduced due to the fact that I
have one resource working on the task for 22.4 hours and the other 9.6 hours
so when I used your explanation I can up with 2.8 days instead of a duration
of 4.

I am tying to get a handle on when to designate fixed units, fixed duration
and fixed work. I have the book Project 2002 by Marmel but I just don't seem
to have a good grasp on when you designate one or the other.

Can you help.

Thanks

John

 

[Steve House [MVP]]

The way I see it, there's no universal set of rules to designate the task
type. Instead, when you edit an assignment, only you can know why you're
doing it. The task type setting is a switch that you can use to insure that
Project recalculates the results of this edit as you intend. This time
around, Task X might be set to Fixed Work. Next week I'm doing another edit
on the same task for another reason and I might set it to Fixed Units or
Fixed Duration. Rather than trying to come up with a rule, just remember
before making any change to ask yourself "Why am I doing this and what is
the intended result?" "When I change X, should Project recalculate Y or Z?"

The same logic applies to the effort-driven versus non-effort-driven
settings. I have a painter assigned to paint a room, expected duration of 5
days. I'm adding another body to the task. If that body is another painter
we'll get the work done in half the time and I'll set it to effort-driven.
But if that body is an assistant, the 5 day estimate was based on the
painter and his assistant working together, and I just haven't put him in
until now, the duration should not change and I want it set to
non-effort-driven behavior.

Here's an interesting example of how to interpret some of these things. I
have two examples of a task that runs 5 days with two resources assigned.
In both examples one resource works 5 hours, the other resource works 40
hours. Total work is thus 45 hours with a duration of 40 hours. In one
example, the 5 hour resource is showing 100% units. In a second example,
the 5 hour resource is showing 12% units. What's the difference? In the
first, the 5 hour resource is coming in full time for a bit over half of the
first day, working with the other guy getting him up to speed, perhaps
training him. Then he goes away and the other fellow continues on by
himself for the rest of the week. In the second example, the 5 hour guy is
the supervisor and he's dropping in for an hour a day, checking in with the
fellow doing the work, trouble shooting, etc.

--
Steve House [MVP]
MS Project Trainer & Consultant
Visit http://www.mvps.org/project/faqs.htm for the FAQs